Pathophysiology and treatment of psychosis in Parkinson's disease: a review

2D-DIGE as a strategy to identify serum protein biomarkers to monitor pharmacological efficacy in dopamine-dictated states of Parkinson's disease and schizophrenia

OBJECTIVES

Parkinson's disease and schizophrenia are clinical scenarios that occur due to dopaminergic deficit and hyperactivity in the midbrain, respectively. Current pharmacological interventions for these two diseases therefore aim to restore normal dopamine levels in the midbrain. But during therapy, there is a overshooting of dopamine concentrations that result in hallucinations in Parkinson's disease patients and extra-pyramidal symptoms in schizophrenic patients. This causes a lot of inconvenience to the patents and the clinicians. There are no tests currently available to monitor drug efficacy in these two neuropsychiatric diseases.

MATERIALS AND METHODS

Parkinson's disease and schizophrenic naïve patients were recruited. Serum proteins isolated from these two clinical phenotypes were labeled with fluorescent cyanine dyes and analyzed by two-dimensional difference in gel electrophoresis proteomic experiment. Differentially expressed spots that had consistent expression pattern across five sets of biological replicate gels were trypsin digested and subjected to mass spectrometric analysis for protein identification. Validation experiments were done for the identified proteins using antibody-based assay on a patient cohort that included naïve, treated, and those who had side effects.

RESULTS

Serum α- and β-globin chains were identified as differentially expressed proteins having threefold higher expressions in Parkinson's patients as compared to schizophrenia. Interestingly, concentrations of these two proteins had an inverse correlation across clinical phenotypes in the dopaminergic spectrum. RBC contamination as a source for these proteins was ruled out.

CONCLUSION

There is a clear association of free serum globin with dopaminergic clinical states. This lays a platform for protein biomarker-based monitoring of pharmacological efficacy in Parkinson's disease and schizophrenia.

Aberrant resting-state oscillatory brain activity in Parkinson's disease patients with visual hallucinations: An MEG source-space study

To gain insight into possible underlying mechanism(s) of visual hallucinations (VH) in Parkinson's disease (PD), we explored changes in local oscillatory activity in different frequency bands with source-space magnetoencephalography (MEG). Eyes-closed resting-state MEG recordings were obtained from 20 PD patients with hallucinations (Hall+) and 20 PD patients without hallucinations (Hall-), matched for age, gender and disease severity. The Hall+ group was subdivided into 10 patients with VH only (unimodal Hall+) and 10 patients with multimodal hallucinations (multimodal Hall+). Subsequently, neuronal activity at source-level was reconstructed using an atlas-based beamforming approach resulting in source-space time series for 78 cortical and 12 subcortical regions of interest in the automated anatomical labeling (AAL) atlas. Peak frequency (PF) and relative power in six frequency bands (delta, theta, alpha1, alpha2, beta and gamma) were compared between Hall+ and Hall-, unimodal Hall+ and Hall-, multimodal Hall+ and Hall-, and unimodal Hall+ and multimodal Hall+ patients. PF and relative power per frequency band did not differ between Hall+ and Hall-, and multimodal Hall+ and Hall- patients. Compared to the Hall- group, unimodal Hall+ patients showed significantly higher relative power in the theta band (p = 0.005), and significantly lower relative power in the beta (p = 0.029) and gamma (p = 0.007) band, and lower PF (p = 0.011). Compared to the unimodal Hall+, multimodal Hall+ showed significantly higher PF (p = 0.007). In conclusion, a subset of PD patients with only VH showed slowing of MEG-based resting-state brain activity with an increase in theta activity, and a concomitant decrease in beta and gamma activity, which could indicate central cholinergic dysfunction as underlying mechanism of VH in PD. This signature was absent in PD patients with multimodal hallucinations.

Controlling selectivity of polymer-based monolithic stationary phases

In this work, we aimed to prepare a monolithic capillary column that allowed an isocratic separation of ten dopamine precursors and metabolites in a single run. Segments of five zwitterion sulfobetaine polymer monoliths have been modified by zwitterion phoshorylcholine by using an ultraviolet-initiated two-step photografting. Columns with 0, 33, 50, 66, and 100% of modified length were prepared. Effect of length of the modified segment and mobile phase composition has been tested. All columns provided dual-retention mechanism with reversed-phase retention in highly aqueous mobile phase and hydrophilic interaction mechanism in highly organic mobile phase. The retention mechanism was controlled by the composition of the mobile phase and has been described by a three-parameter model. We have used regression parameters to characterize the retention of analyzed compounds and to study individual pathways of dopamine metabolism. Comprehensive optimization of mobile phase composition allowed to find an optimal composition of the mobile phase and stationary phase surface chemistry arrangement to achieve desired separation. Optimized columns provided an isocratic separation of all tested compounds in less than nine min.

Cerebrospinal Fluid Proteomics For Identification Of α2-Macroglobulin As A Potential Biomarker To Monitor Pharmacological Therapeutic Efficacy In Dopamine Dictated Disease States Of Parkinson's Disease And Schizophrenia

AIM

Parkinson's disease and schizophrenia are clinical end points of dopaminergic deficit and excess, respectively, in the mid-brain. In accordance, current pharmacological interventions aim to restore normal dopamine levels, the overshooting of which culminates in adverse effects which results in psychotic symptoms in Parkinson's disease and extra-pyramidal symptoms in schizophrenia. Currently, there are no laboratory assays to assist treatment decisions or help foresee these drug side-effect outcomes. Therefore, the aim was to discover a protein biomarker that had a varying linear expression across the clinical dopaminergic spectrum.

MATERIALS AND METHODS

iTRAQ-based proteomic experiments along with mass spectrometric analysis was used for comparative proteomics using cerebrospinal fluid (CSF). CSF fluid was collected from 36 patients with Parkinson's disease, 15 patients with urological diseases that served as neurological controls, and seven schizophrenic patients with hallucinations. Validation included ELISA and pathway analysis to highlight the varying expression and provide plausible molecular pathways for differentially expressed proteins in the three clinical phenotypes.

RESULTS

Protein profiles were delineated in CSF from Parkinson's disease patients, neurological control and schizophrenia, respectively. Ten of the proteins that were identified had a linear relationship across the dopaminergic spectrum. α-2-Macroglobulin showed to be having high statistical significance on inter-group comparison on validation studies using ELISA.

CONCLUSIONS

Non-gel-based proteomic experiments are an ideal platform to discover potential biomarkers that can be used to monitor pharmaco-therapeutic efficacy in dopamine-dictated clinical scenarios. α-2 Macroglobulin is a potential biomarker to monitor pharmacological therapy in Parkinson's disease and schizophrenia.

Pimavanserin for Parkinson's Disease psychosis: Effects stratified by baseline cognition and use of cognitive-enhancing medications

BACKGROUND

PD psychosis is often associated with cognitive impairment, including dementia, and involves dopaminergic, serotonergic, and cholinergic mechanisms.

OBJECTIVE

To evaluate the differential effect of the antipsychotic pimavanserin, a selective serotonin 2A receptor inverse agonist, in PD psychosis patients with versus without cognitive impairment and in those receiving versus not receiving cognitive-enhancing medications.

METHODS

Data from the pivotal randomized clinical trial of pimavanserin for PD psychosis were stratified by (1) screening MMSE score as cognitively impaired (21-24) versus unimpaired (≥25) and (2) concomitant use versus nonuse of cognitive-enhancing medications. The primary outcome measure was change in the PD-adapted Scale for the Assessment of Positive Symptoms.

RESULTS

Mean (pimavanserin vs. placebo) change from baseline was larger in the cognitively impaired (n = 50; -6.62 vs. -0.91; P = 0.002) versus the cognitively unimpaired (n = 135; -5.50 vs. -3.23; p = 0.046) group. The comparable change was -6.04 versus -2.18 (P = 0.012) and -5.66 versus -3.15 (P = 0.041) in patients treated (n = 69) and not treated (n = 116) with concomitant cognitive-enhancing medication. Pimavanserin was similarly tolerated across all cognitive groups with no additional safety concerns identified. Overall adverse event rates were comparable across the concomitant cognitive-enhancing medication groups; however, rates of serious adverse events and discontinuations attributed to adverse events were increased in patients taking cholinesterase inhibitors.

CONCLUSIONS

The antipsychotic effect of pimavanserin is robust in PD patients with cognitive impairment and may be enhanced by concomitant cognitive-enhancing medication use. Future prospective studies are needed to confirm these preliminary findings. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Evaluation of Serum Apolipoprotein E as a Potential Biomarker for Pharmacological Therapeutic Efficacy Monitoring in Dopamine Dictated Disease Spectrum of Schizophrenia and Parkinson's disease: A Preliminary Study

AIM OF THE STUDY

Parkinson's disease and schizophrenia are disease end points of dopaminergic deficit and hyperactivity, respectively, in the mid brain. Accordingly, current medications aim to restore normal dopamine levels, overshooting of which results in adverse effects of psychosis and extra-pyramidal symptoms, respectively. There are currently no available laboratory tests to guide treatment decisions or help predict adverse side effects of the drugs. The aim was to therefore explore the possibility of using apolipoprotein E as a biomarker to monitor pharmacological intervention in dopamine dictated states of Parkinson's disease and schizophrenia for optimum therapy.

METHODS

Naïve and treated, Parkinson's disease and schizophrenic patients were recruited from neurology and psychiatry clinics. Serum of healthy volunteers was collected as controls. Serum concentrations of apolipoprotein E was estimated by enzyme-linked immunosorbent assay (ELISA). Pathway analysis was carried out to delineate the interactions of apolipoprotein E in Parkinson's disease and schizophrenia.

RESULTS

Apolipoprotein E levels are higher in Parkinson's disease patients as compared with schizophrenic samples (P < .05). Also, post-treatment apolipoprotein E levels in both disease states were at par with levels seen in healthy controls. The interactions of apolipoprotein E validate the results and place the differential expression of the protein in Parkinson's disease and schizophrenia in the right perspective.

CONCLUSION

Apolipoprotein E concentration across the dopaminergic spectrum suggests that it can be pursued not only as a potential biomarker in schizophrenia and Parkinson's disease, but can also be an effective tool for clinicians to determine efficacy of drug-based therapy.

Pimavanserin (Nuplazid™) for the treatment of Parkinson disease psychosis: A review of the literature

Introduction:

Pimavanserin (Nuplazid™) is an atypical antipsychotic currently indicated for the treatment of hallucinations and delusions associated with Parkinson disease psychosis. The antipsychotic effects of this new agent are believed to occur via selective inverse agonist activity at serotonin 5-HT_2a receptors.

Methods:

Study authors completed a literature review of 2 published randomized controlled trials of pimavanserin for the treatment of Parkinson disease psychosis. The Food and Drug Administration Briefing Document by the Psychopharmacologic Drugs Advisory Committee for the review of pimavanserin dated March 29, 2016, was reviewed for additional information on 2 unpublished trials.

Results:

Pimavanserin has demonstrated no worsening of motor symptoms of Parkinson disease, but only 1 of 4 trials has shown consistent statistically significant improvements in psychotic symptoms compared with placebo.

Discussion:

Options for the treatment of Parkinson disease psychosis are limited. The selective receptor profile of pimavanserin offers advantages for tolerability. Further studies are warranted to better provide clinicians and patients with information regarding the clinical utility of this agent.

Molecular targets of atypical antipsychotics: From mechanism of action to clinical differences

The introduction of atypical antipsychotics (AAPs) since the discovery of its prototypical drug clozapine has been a revolutionary pharmacological step for treating psychotic patients as these allow a significant recovery not only in terms of hospitalization and reduction in symptoms severity, but also in terms of safety, socialization and better rehabilitation in the society. Regarding the mechanism of action, AAPs are weak D₂ receptor antagonists and they act beyond D₂ antagonism, involving other receptor targets which regulate dopamine and other neurotransmitters. Consequently, AAPs present a significant reduction of deleterious side effects like parkinsonism, hyperprolactinemia, apathy and anhedonia, which are all linked to the strong blockade of D₂ receptors. This review revisits previous and current findings within the class of AAPs and highlights the differences in terms of receptor properties and clinical activities among them. Furthermore, we propose a continuum spectrum of "atypia" that begins with risperidone (the least atypical) to clozapine (the most atypical), while all the other AAPs fall within the extremes of this spectrum. Clozapine is still considered the gold standard in refractory schizophrenia and in psychoses present in Parkinson's disease, though it has been associated with adverse effects like agranulocytosis (0.7%) and weight gain, pushing the scientific community to find new drugs as effective as clozapine, but devoid of its side effects. To achieve this, it is therefore imperative to characterize and compare in depth the very complex molecular profile of AAPs. We also introduce relatively new concepts like biased agonism, receptor dimerization and neurogenesis to identify better the old and new hallmarks of "atypia". Finally, a detailed confrontation of clinical differences among the AAPs is presented, especially in relation to their molecular targets, and new means like therapeutic drug monitoring are also proposed to improve the effectiveness of AAPs in clinical practice.

Investigation of the Pharmaceutical Care in One Elderly Parkinson's Disease Patient with Psychotic Symptoms

A 66-year-old male patient with a 10-year course of Parkinson's disease (PD) was admitted for hallucination lasting a half a month. After treatment with levodopa/carbidopa, selegiline, and piribedil, the patient's motor symptoms were improved while no significant effects were observed on psychotic symptoms. A clinical pharmacist analyzed the pharmacologic and pharmacokinetic characteristics of selegiline and piribedil, summarized the scheme of PD with psychotic symptoms in the literature, and discovered that selegiline might potentiate psychotic side effects of piribedil, while the use of levodopa/carbidopa cannot be ruled out either. Finally, the clinical pharmacist proposed to reduce the dosage of levodopa/carbidopa, increase the dosage of selegiline and quetiapine, and discontinue piribedil. The clinician accepted this suggestion. After the adjustment of medication, the patient's motor symptoms were absolutely improved and the psychotic symptoms were notably improved. This case study suggests that long-term treatment with levodopa/carbidopa and piribedil, along with the progression of the disease itself, could contribute to the emergence of psychotic symptoms in PD. Additionally, selegiline could potentiate psychotic side effects of piribedil. Neurology clinical pharmacists should work alongside neurology clinicians at the bedside to optimize pharmacotherapy, improve patient safety, and contribute to scholarly efforts.

Genetics and Treatment Response in Parkinson's Disease: An Update on Pharmacogenetic Studies

Parkinson's disease (PD) is a complex neurodegenerative disorder characterized by a progressive loss of dopamine neurons of the central nervous system. The disease determines a significant disability due to a combination of motor symptoms such as bradykinesia, rigidity and rest tremor and non-motor symptoms such as sleep disorders, hallucinations, psychosis and compulsive behaviors. The current therapies consist in combination of drugs acting to control only the symptoms of the illness by the replacement of the dopamine lost. Although patients generally receive benefits from this symptomatic pharmacological management, they also show great variability in drug response in terms of both efficacy and adverse effects. Pharmacogenetic studies highlighted that genetic factors play a relevant influence in this drug response variability. In this review, we tried to give an overview of the recent progresses in the pharmacogenetics of PD, reporting the major genetic factors identified as involved in the response to drugs and highlighting the potential use of some of these genomic variants in the clinical practice. Many genes have been investigated and several associations have been reported especially with adverse drug reactions. However, only polymorphisms in few genes, including DRD2, COMT and SLC6A3, have been confirmed as associated in different populations and in large cohorts. The identification of genomic biomarkers involved in drug response variability represents an important step in PD treatment, opening the prospective of more personalized therapies in order to identify, for each person, the better therapy in terms of efficacy and toxicity and to improve the PD patients' quality of life.

Antipsychotics in people with dementia: frequency of use and rationale for prescribing in a UK mental health service

Aims and method

To determine how often and why antipsychotic medicines are prescribed to people with dementia. A cross-sectional survey of all clinical records was conducted in one National Health Service mental health trust.

Results

Of 946 people with dementia in the trust, 186 (20%) were prescribed an antipsychotic. Prevalence increased with the severity of dementia. The most common indication for initiating treatment was agitation/distress (70%), followed by verbal aggression (45%), psychotic symptoms (44%) and physical aggression (33%). The mean number of indications per patient was 2.6. In 58% of cases, the antipsychotic had been prescribed for more than a year, and a third of patients had not been reviewed in the past 6 months.

Clinical implications

People with dementia who are prescribed antipsychotic drugs generally display a range of challenging behaviours, but most notably are distressed. Systems for ongoing clinical review need improvement.

Adverse psychiatric effects of non-psychotropic medications

Patients presenting to psychiatrists frequently have comorbid medical conditions for which they are receiving treatment. A range of medications used for treatment of these conditions can have adverse effects resembling psychiatric symptoms. This article presents the results of our review of the literature on psychiatric adverse effects of various non-psychotropic medications, and discusses the mechanisms of such effects, their assessment and management. Among the commonly prescribed drugs found to have psychiatric adverse effects are corticosteroids, anti-Parkinsonian drugs, anti-epileptics, antiretrovirals, antibiotics, anticancer drugs, analgesics, drugs targeting endocrine and cardiovascular disorders, immunosuppressants, skeletal muscle relaxants and bronchodilators. Some adverse effects are predictable and dose dependent, whereas others are rare and idiosyncratic, and psychiatrists need to be aware of them for accurate diagnosis and appropriate treatment.

Parkinson's disease psychosis: presentation, diagnosis and management

Parkinson's disease is a neurodegenerative disorder characterized by motor and nonmotor symptoms. Psychosis is a common feature of Parkinson's disease. Parkinson's disease psychosis (PDP) encompasses minor phenomena (illusions, passage hallucinations and presence hallucinations), visual and nonvisual hallucinations and delusions. PDP is associated with reduced function and quality of life. The initial management approach should focus on identification and treatment of any contributory medical factors, reduction or discontinuation of medications with potential to induce or worsen psychosis, nonpharmacological strategies and consideration of acetylcholinesterase inhibitor treatment in the setting of dementia. Pimavanserin, quetiapine and clozapine may all be considered for use in PDP. In this review, we discuss the presentation, diagnosis and management of PDP.

Pimavanserin, a novel antipsychotic for management of Parkinson's disease psychosis

INTRODUCTION

Parkinson's disease psychosis (PDP) may develop in up to 60% of Parkinson's patients and is associated with increased morbidity and mortality. It also correlates with depression and dementia, and can contribute to caregiver stress and burnout. Pimavanserin is the first FDA approved drug for the treatment of hallucinations and delusions associated with PDP. Areas covered: For this review, a MEDLINE literature search (via PubMed) and information provided by ACADIA Pharmaceuticals were used. This review will discuss the pathophysiology and current management of PDP. In addition, this review will focus on the rationales behind the development of pimavanserin, mechanism of action, pharmacokinetics, pharmacodynamics, and the clinical trials evaluating the efficacy and safety of pimavanserin. Last, the review will address the drug's package insert warning. Expert commentary: Pimavanserin, a 5HT2A receptor inverse agonist, is the first FDA approved drug for the treatment of PDP which has been shown to reduce psychosis in PD through its unique mechanism of action. Pimavanserin, does not worsen PD motor symptoms and has an acceptable safety profile. The development of pimavanserin as an antipsychotic opened a new therapeutic avenue in the treatment of PDP as well as targeting psychosis in other disorders such as Alzheimer's disease.

Psychosis in Parkinson Disease: A Review of Etiology, Phenomenology, and Management

Parkinson disease psychosis (PDP) is a common phenomenon in Parkinson disease (PD) patients treated with dopaminergic drugs, and is associated with high morbidity and mortality. It also correlates with depression and dementia, and can contribute to considerable caregiver stress and burnout. While symptoms can be relieved by decreasing doses or number of anti-PD medications, this may lead to an unacceptable worsening of motor function. When general medical or psychiatric conditions have been ruled out, and decreasing dopaminergic agents is not effective in treating psychosis, therapies include atypical antipsychotics, primarily clozapine and quetiapine. Of these, clozapine is effective but is associated with a poor side-effect profile and the necessity for frequent blood draws. Clinicians prefer quetiapine for its theoretically better safety profile, although there is no evidence for efficacy in treating psychosis. All atypical antipsychotics are associated with increased mortality in this patient population. Cholinesterase inhibitors can ameliorate psychosis symptoms. The serotonin 5-HT_2A receptor inverse agonist pimavanserin was recently approved by the US FDA for the treatment of PDP and may prove to be a more targeted therapy without the downsides of atypical antipsychotics.

Non-motor features of Parkinson disease

Many of the motor symptoms of Parkinson disease (PD) can be preceded, sometimes for several years, by non-motor symptoms that include hyposmia, sleep disorders, depression and constipation. These non-motor features appear across the spectrum of patients with PD, including individuals with genetic causes of PD. The neuroanatomical and neuropharmacological bases of non-motor abnormalities in PD remain largely undefined. Here, we discuss recent advances that have helped to establish the presence, severity and effect on the quality of life of non-motor symptoms in PD, and the neuroanatomical and neuropharmacological mechanisms involved. We also discuss the potential for the non-motor features to define a prodrome that may enable the early diagnosis of PD.

Imaging the Nonmotor Symptoms in Parkinson's Disease

Parkinson's disease is acknowledged to be a multisystem syndrome, manifesting as a result of multineuropeptide dysfunction, including dopaminergic, cholinergic, serotonergic, and noradrenergic deficits. This multisystem disorder ultimately leads to the presentation of a range of nonmotor symptoms, now appreciated to be an integral part of the disease-specific spectrum of symptoms, often preceding the diagnosis of motor Parkinson's disease. In this chapter, we review the dopaminergic and nondopaminergic basis of these symptoms by exploring the neuroimaging evidence based on several techniques including positron emission tomography, single-photon emission computed tomography molecular imaging, magnetic resonance imaging, functional magnetic resonance imaging, and diffusion tensor imaging. We discuss the role of these neuroimaging techniques in elucidating the underlying pathophysiology of NMS in Parkinson's disease.

Cortical and Striatal Reward Processing in Parkinson's Disease Psychosis

Psychotic symptoms frequently occur in Parkinson's disease (PD), but their pathophysiology is poorly understood. According to the National Institute of Health RDoc programme, the pathophysiological basis of neuropsychiatric symptoms may be better understood in terms of dysfunction of underlying domains of neurocognition in a trans-diagnostic fashion. Abnormal cortico-striatal reward processing has been proposed as a key domain contributing to the pathogenesis of psychotic symptoms in schizophrenia. This theory has received empirical support in the study of schizophrenia spectrum disorders and preclinical models of psychosis, but has not been tested in the psychosis associated with PD. We, therefore, investigated brain responses associated with reward expectation and prediction error signaling during reinforcement learning in PD-associated psychosis. An instrumental learning task with monetary gains and losses was conducted during an fMRI study in PD patients with (n = 12), or without (n = 17), a history of psychotic symptoms, along with a sample of healthy controls (n = 24). We conducted region of interest analyses in the ventral striatum (VS), ventromedial prefrontal and posterior cingulate cortices, and whole-brain analyses. There was reduced activation in PD patients with a history of psychosis, compared to those without, in the posterior cingulate cortex and the VS during reward anticipation (p < 0.05 small volume corrected). The results suggest that cortical and striatal abnormalities in reward processing, a putative pathophysiological mechanism of psychosis in schizophrenia, may also contribute to the pathogenesis of psychotic symptoms in PD. The finding of posterior cingulate dysfunction is in keeping with prior results highlighting cortical dysfunction in the pathogenesis of PD psychosis.

Dopamine and serotonin modulation of motor and non-motor functions of the non-human primate striato-pallidal circuits in normal and pathological states

Thanks to the non-human primate (NHP), we have shown that the pharmacological disturbance of the anterior striatum or of external globus pallidus triggers a set of motivation and movement disorders, depending on the functional subterritory involved. One can, therefore, assume that the aberrant activity of the different subterritories of basal ganglia (BG) could lead to different behavioral disorders in neuropsychiatric disorders as Tourette's syndrome and Parkinson's disease. We are now addressing in the NHP the impact of modulating dopamine or serotonin within the BG on behavioral disorders. Indeed, we have shown a prominent role of serotonergic degeneration within the ventral striatum and caudate nucleus in neuropsychiatric symptoms in de novo PD patients. Of note, the serotonergic modulation of these BG regions in the NHP plays also a critical role in the induction or treatment of behavioral disorders. Given that both dopamine and serotonin are targeted to treat neuropsychiatric disorders, we are studying the effects of modulating dopamine and serotonin transporters in the different territories of the striatum, and more particularly within the ventral striatum on decision-making processing at both behavioral and neuronal levels. Finally, we evidence the need to extend the pharmacological approach to the receptors of these two neuromodulator systems as the use of substances targeting receptor subtypes preferentially localized in the associative and limbic territories of BG could be very effective to specifically improve the behavioral disorders in Parkinson's disease, Gilles de la Tourette syndrome but also in several psychiatric disorders such as depression, anxiety, anorexia, or impulse control disorders.

Delusional Infestation in Parkinson's Disease

Delusional infestation (DI), a form of psychosis, has rarely been reported in patients with Parkinson disease (PD). The clinical presentation and successful treatment of DI is illustrated through 5 cases. Each patient developed DI during treatment for moderate to advanced Parkinson's disease, and only 2 had cognitive impairment. Two patients were on monotherapy: 1 on a dopamine agonist and the other on trihexyphenidyl. Three patients were receiving complex combination therapy with 2 to 5 different anti-Parkinsonian medications at the onset of their delusion. Selective discontinuation or reduction of these medications was key to the resolution of DI in each patient. Although the medication adjustments differed, the changes resulted in the reduction of anticholinergic effects or extracellular striatal dopamine levels. This series emphasizes the clinical features and management strategies for this disruptive form of psychosis in patients with PD.

Update on the treatment of Parkinson's disease psychosis: role of pimavanserin

Parkinson's disease (PD) has a prevalence of nearly 1 million people in the USA, with increasing incidence in the elderly population. Generally, the age of presentation is between 55 and 65 years, with the likelihood of diagnosis increasing as patients reach the age of 80 years or above. Some of the common treatments for PD increase dopamine levels in the brain. Dopaminergic therapy helps to improve motor and non-motor symptoms, but it is not without risks. Dopaminergic therapy can cause confusion, delirium, and psychotic-like behavior. It is recommended that these agents are used cautiously in patients with a history of psychosis due to the risk of exacerbation. It is unclear whether Parkinson's disease psychosis (PDP) is due to the disease itself, the treatment, or a combination of both, but it is clear that a safe, effective treatment is necessary. Second-generation (atypical) antipsychotics are the current choice of therapy for PDP. All of these agents have a black box warning from the US Food and Drug Administration (FDA) for elevated risk of mortality in elderly patients with dementia-related psychosis. Pimavanserin (Nuplazid^®) received its novel drug approval by the FDA on April 29, 2016, to treat hallucinations and delusions associated with psychosis experienced by some people with PD. We review in this article the new research that led to this approval as well as its potential place in therapy.

Pharmacotherapies for Parkinson's disease symptoms related to cholinergic degeneration

INTRODUCTION

Dopamine depletion is one of the most important features of Parkinson's Disease (PD). However, insufficient response to dopaminergic replacement therapy suggests the involvement of other neurotransmitter systems in the pathophysiology of PD. Cholinergic degeneration contributes to gait impairments, cognitive impairment, psychosis, and REM-sleep disturbances, among other symptoms. Areas covered: In this review, we explore the idea that enhancing cholinergic tone by pharmacological or neurosurgical procedures could be a first-line therapeutic strategy for the treatment of symptoms derived from cholinergic degeneration in PD. Expert opinion: Rivastigmine, a drug that increases cholinergic tone by inhibiting the enzyme cholinesterase, is effective for dementia, whereas the use of Donepezil is still in the realm of investigation. Interesting results suggest the efficacy of these drugs in the treatment of gait dysfunction. Evidence on the clinical effects of these drugs for psychosis and REM-sleep disturbances is still weak. Stimulation of the pedunculo-pontine tegmental nuclei (which provide cholinergic innervation to the brain stem and subcortical nuclei) has also been used with some success for the treatment of gait dysfunction. Anticholinergic drugs should be used with caution in PD, as they may aggravate cholinergic symptoms. Notwithstanding, in some patients they might help control parkinsonian motor symptoms.

Medical mimics: Differential diagnostic considerations for psychiatric symptoms

Patients with underlying medical disease can present to the health care system with psychiatric symptoms predominating. Identification of an underlying medical condition masquerading as a psychiatric disorder can be challenging for clinicians, especially in patients with an existing psychiatric condition. The term medical mimic or secondary psychosis has been used to describe this clinical situation. Diagnostic categories from The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, that may encompass medical mimics include substance-induced disorders, which includes medications, and unspecified mental disorder due to another medical condition in situations where the clinician may lack needed information for a complete diagnosis. At this time, there is no single diagnostic test or procedure available to differentiate primary versus secondary psychosis on the basis of psychopathology presentation alone. When considering a diagnosis, clinicians should evaluate for the presence of atypical features uncharacteristic of the psychiatric symptoms observed; this may include changes in functionality and/or age of onset and symptom presentation severity. The purpose of this work is to provide a structured clinical framework for evaluation for medical mimics, identify groups considered to be at highest risk for medical mimics, and present common syndromic features suggestive of a medical mimic. Selected case scenarios are used to illustrate key concepts for evaluating and assessing a patient presenting with acute psychiatric symptomatology to improve judgment in ruling out potential medical causality.

Evidence for the use of pimavanserin in the treatment of Parkinson's disease psychosis

Parkinson's disease (PD) is a progressive neurodegenerative disorder with both motor and nonmotor symptoms (NMS), leading to significant morbidity and caregiver burden. Psychosis is common but is under recognized by physicians. When present, it increases the patient's risk of hospitalization and nursing home placement and caregiver burden. Although the atypical antipsychotic agent, clozapine, has been considered the gold standard treatment, severe agranulocytosis in 0.38% of patients and more commonly milder leukopenia, resulting in frequent blood testing, limit its use. Pimavanserin, a 5HT2A receptor inverse agonist, has been shown to reduce psychosis in PD without worsening motor symptoms. It is therefore a welcome therapeutic option for this devastating NMS.

Prevalence and risk factors for visual hallucinations in Chinese patients with Parkinson's disease

BACKGROUND AND PURPOSE

Parkinson's disease (PD) patients frequently present visual hallucinations (VHs)·The determinants of VHs in Chinese PD patients remain largely unknown. The aim of this study was to illuminate the prevalence and clinical correlates of VHs in the Chinese population with PD.

METHODS

A total of 371 consecutive, idiopathic PD patients were recruited into the study. Patients were categorized as hallucinators and nonhallucinators according to Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS).

RESULTS

VHs were observed in 72 (19.4%) patients. Among them, 26.4% of the hallucinators experienced minor hallucinations, and 73.6% had complex visual hallucinations. The age, disease duration, percentage of patients using dopamine agonists, UPDRS part III, Hoehn and Yahr (H-Y) stage, and Non-Motor Symptoms Questionnaire (NMS-Quest) score in hallucinators were significantly greater than in nonhallucinators (P<0.05). The Montreal Cognitive Assessment (MOCA) and PD Sleep Scale (PDSS) scores in nonhallucinators were significantly higher than in hallucinators (P<0.05). The Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) scores were not different between the hallucinators and nonhallucinators. The forward binary logistic regression model showed that disease duration, dopamine agonist use, sleep quality, and cognition were associated with VHs in PD patients.

CONCLUSIONS

Our results confirm the high prevalence of VHs in patients with PD. The VHs are associated with duration, dopamine agonist use, sleep quality, and cognition, and should trigger further inquiry by neurologists.

Parkinson's disease psychosis as a serotonin-dopamine imbalance syndrome

Parkinson's disease psychosis (PDP) is theoretically a serotonin-dopamine imbalance syndrome due to disruption of the normal balance between the serotonergic and dopaminergic neurotransmitter systems in key brain circuits.

Current Understanding of Psychosis in Parkinson's Disease

Psychosis in Parkinson's disease (PD) is one of the greatest determinants of nursing home placement and caregiver stress. Traditionally associated with medications with dopaminergic effect, it has now been linked to other medications and other stressors e.g. systemic illnesses. The development of hallucinations in a PD patient can herald the onset of dementia and usually predicts increased mortality risk. Medication reduction in PD psychosis usually reduces the symptoms; however, this comes at the cost of worsening motor function. If gradually decreasing the patient's medications does not resolve the psychosis, the treatment of choice is an atypical antipychotic. Though only clozapine has level A recommendation for this indication, other atypicals like quetiapine continue to get used for this purpose on account of the logistics involved with clozapine use. Cholinesterase inhibitors are also increasingly being used for PD psychosis on account of the association with dementia. The treatment of PD psychosis is an unmet need in PD management and search for suitable agents constitutes an active area of research in PD.

Polymorphisms of dopamine receptor genes and risk of visual hallucinations in Parkinson's patients

BACKGROUND

Visual hallucinations (VHs) are frequent non-motor complication of Parkinson's disease (PD), associated to a negative prognosis. Previous studies showed an association between dopamine receptor (DR) gene (DR) variants and psychosis in Alzheimer's disease, addictions, schizophrenia, and bipolar disorder. However, there are only a few studies on DR variants and VHs in PD, which did not provide conclusive results.

OBJECTIVES

The present study aimed to determine whether genetic differences of DR are associated with visual hallucinations (VHs) in a cohort of Parkinson's disease (PD) patients.

METHODS

A case-control study of 84 PD subjects, 42 with and 42 without VHs,that were matched for age, gender, disease duration, and dopaminergic medication was conducted. Polymerase chain reaction for SNPs in both D1-like (DRD1A-48G [rs4532] and C62T [rs686], DRD5T798C [rs6283]) and D2-like DR (DRD2G2137A [rs1800497] and C957T [rs6277], DRD3G25A [rs6280] and G712C [rs1800828], DRD4C616G [rs747302] and nR VNTR 48bp) analyzed genomic DNA.

RESULTS

Patients carrying allele T at DRD1C62T had an increased risk of VHs, expressed as OR (95 % CI, p value), of 10.7 (2.9-40, p = 0.0001). Moreover, patients with DRD1-48 GG and 62TT genotype displayed shorter time to VHs, whereas a longer time to VHs was found in subjects carrying the DRD4 CG alleles.

CONCLUSIONS

PD patients with VHs display higher frequency of DR SNPs associated with increased D1-like activity and decreased D2-like activity. Our data are in line with associations reported in other neurodegenerative and psychiatric conditions. Results likely provide valuable information for personalizing pharmacological therapy in PD patients.

Parkinson's disease psychosis: therapy tips and the importance of communication between neurologists and psychiatrists

Parkinson's disease (PD) is a chronic and complex neurodegenerative disorder resulting in a mixture of motor and nonmotor symptoms. Psychosis develops in around 60% of PD patients during and can be one of the most challenging nonmotor symptoms. PD psychosis is considered the single greatest precipitant for nursing home placement. PD psychosis is an independent predictor of increased mortality, and there is no 'ideal' or universal treatment strategy. The treatment approach to PD psychosis should be tailored and individualized for each patient. In this review, we will discuss PD psychosis and provide practical treatment considerations for neurologists, psychiatrists and other healthcare professionals. We stress the importance of real-time communication between members of the healthcare team.

Mechanism of action of pimavanserin in Parkinson's disease psychosis: targeting serotonin 5HT2A and 5HT2C receptors

Pimavanserin, a novel agent approved for the treatment of Parkinson's disease psychosis, has potent actions as an antagonist/inverse agonist at serotonin 5HT2A receptors and less potent antagonist/inverse agonist actions at 5HT2C receptors.

Neuropsychiatric Symptoms in Parkinson's Disease

Parkinson's disease (PD) is characterized by motor symptoms, but focused and extensive research in the last years has provided new knowledge in the field of non-motor symptoms. Non-motor symptoms include neuropsychiatric symptoms such as depression, anxiety, psychosis, apathy, impulse control disorders, and occur in the majority of patients with PD. They are associated with impaired quality of life for patients and relatives, additional deterioration of function and increased use of health resources. Medical and surgical therapies commonly used for treatment of PD can induce or worsen such symptoms. This paper discusses the epidemiology, clinical features and treatment approaches for neuropsychiatric symptoms (NPS) in PD in the perspective of clinical practice and management. The prevalence rates of various NPS are high, various demographic, clinical and treatment related variables have shown to be associated with higher risk of NPS. Randomized controlled trials of pharmacological and non-pharmacological treatments of NPS in PD are sparse. Current evidence supports tricyclic antidepressants as efficacious treatment of depression in PD and antipsychotic clozapine as efficacious choice for psychosis. Further studies to evaluate various other management strategies of NPS in PD are required. Neuropsychiatric symptoms in PD should be considered an integral part of the disease; hence a multidisciplinary approach is essential to improve the overall outcome of PD also through raised awareness and enriched knowledge on NPS.

The Efficacy and Safety of Antipsychotic Medications in the Treatment of Psychosis in Patients with Parkinson's Disease

Psychotic symptoms are present in up to 50% of patients with Parkinson's disease. These symptoms have detrimental effects on patients' and caregivers' quality of life and may predict mortality. The pathogenesis of psychotic symptoms in Parkinson's disease is complex, but the use of dopaminergic medications is one of the risk factors. The treatment of psychotic symptoms in Parkinson's disease is complicated due to the ability of antipsychotic medications to worsen motor symptoms. The efficacy of clozapine in the treatment of psychosis in patients with Parkinson's disease has been confirmed in several clinical trials; however, the adverse effects and the necessity of blood count monitoring are the reasons why the use of this drug is challenging. The studies on safety and efficacy of other antipsychotics conflicting results. The use of antipsychotics in these patients is also associated with increased mortality. Psychotic symptoms in Parkinson's disease per se are also proven predictors of mortality. Thus it is necessary to treat psychotic symptoms but the choice of an antipsychotic should be based on careful risk/benefit assessment. Pimavanserin as a novel therapeutic option with more favorable adverse effects profile is now available for this indication, but careful postmarketing monitoring is necessary to establish the true picture of this drug's long-term safety and efficacy.

Distinguishing Neuroimaging Features in Patients Presenting with Visual Hallucinations

Visual hallucinations are relatively uncommon presentations in medical and psychiatric clinics, where they are generally regarded as a marker of possible underlying "organic" brain disease. Thus, patients with visual hallucinations are often referred for imaging of the brain. This article presents a pragmatic approach for the radiologist reviewing such imaging. Because conditions that can present with visual hallucinations are legion, a familiarity with the features of the hallucinations themselves, which can serve as clues to the underlying cause, can be helpful in interpreting such cases. We consider the nature of visual hallucinations and the mechanisms underlying their formation. We then provide a framework to guide the search for their cause, first in terms of focal lesions along the visual pathway and then global conditions affecting >1 region.

Behavioral effects of clozapine, pimavanserin, and quetiapine in rodent models of Parkinson's disease and Parkinson's disease psychosis: evaluation of therapeutic ratios

No safe, tolerated, and effective treatment for Parkinson's disease psychosis (PDP) is available; however, clozapine and quetiapine are often used off-label. An ideal PDP drug should have a therapeutic window that alleviates psychotic symptoms at doses that allow for maintained motor control and do not cause sedation. The present study determined the effective doses of quetiapine, clozapine, and the nondopaminergic, selective 5-HT2A inverse agonist/antagonist, pimavanserin, in an animal model of PDP and compared them with the doses that caused dopamine blockade and sedation. Augmented amphetamine-induced locomotion in rats with bilateral substantia nigra lesions was used to assess antipsychotic efficacy, whereas blockade of apomorphine-induced rotations in rats with unilateral 6-hydroxydopamine lesions was used to assess antidopaminergic action and reduction in spontaneous locomotion was used to assess sedation. The estimated therapeutic ratios for clozapine and quetiapine varied between 0.81 and 3.3. In contrast, the estimated therapeutic ratios for pimavanserin were at or above 170. These results suggest that a selective 5-HT2A inverse agonist/antagonist, such as pimavanserin, may provide distinct advantages compared with clozapine or quetiapine as a therapy for PDP.

Genetic substrates of psychosis in patients with Parkinson's disease: A critical review

Patients with Parkinson's disease (PD) may develop several non-motor symptoms such as psychosis, depression, cognitive impairment, autonomic disturbances and sleep disturbances. Psychosis is one of the common non-motor symptoms, which commonly manifests as visual hallucinations and minor hallucinations such as sense of passage and presence. Though long-term dopaminergic therapy, longer duration of PD and cognitive impairment have been described as risk factors for emergence of psychosis in PD, predicting psychosis in PD remains challenging. Multiple studies have explored the genetic basis of psychosis in PD by studying polymorphisms of several genes. Most of the studies have focused on apolipoprotein E polymorphism followed by polymorphisms in cholecystokinin (CCK) system, dopamine receptors and transporters, HOMER gene, serotonin, catechol-o-methyltransferase, angiotensin converting enzyme and tau. Other than the studies on polymorphisms of CCK, most of the studies have reported conflicting results regarding association with psychosis in PD. Three out of four studies on CCK polymorphism have reported significant association of -45C>T polymorphism with the presence of hallucinations. The discrepancies in the results across the studies reviewed are possibly due to racial differences as well as differences in the patient characteristics. This review critically analyzes the published studies on genetic polymorphisms in patients with PD and psychosis.

Worldwide Differences in Regulations of Clozapine Use

Clozapine remains the drug of choice for treatment-resistant schizophrenia. As a consequence of its long history and complex pharmacology, we suspected wide variation in the regulations of clozapine use across different countries. The summaries of product characteristics (SPCs) from clozapine manufacturers, as well as local and national guidelines in the following selected countries, were reviewed: China, Denmark, Ireland, Japan, The Netherlands, New Zealand, Romania, the UK and the US. Clozapine is available as tablets in all countries, as an oral suspension in all included countries, with the exception of Japan and Romania, as orally disintegrating tablets in the US and China, and as an injectable in The Netherlands. General practitioner prescribing is only available in The Netherlands, New Zealand, the UK and the US, although with some restrictions in some of the countries. In Ireland and China, clozapine is only dispensed through hospital pharmacies. Hematological monitoring is mandatory in all countries but varies substantially in frequency, e.g. in Denmark hematologic monitoring is mandatory weekly for 18 weeks, followed by monthly monitoring, compared with Japan where blood work is required weekly for 26 weeks, followed by biweekly hematologic monitoring thereafter. In most included countries, with the exception of Denmark, Romania and The Netherlands, the manufacturer provides a mandatory hematological monitoring database, and dispensing of clozapine is not permissible without acceptable white blood count and absolute neutrophil count results. Local guidelines in New Zealand recommend echocardiography and routine troponin during the initial phases of treatment with clozapine. Regulations of clozapine vary widely with regard to rules of prescribing and monitoring. A worldwide update and harmonization of these regulations is recommended.

High prolactin levels are associated with more delirium in septic patients

PURPOSES

We investigated whether high prolactin levels were associated with delirium in septic patients because neuropsychiatric disorders are frequently associated with hyperprolactinemia.

MATERIALS AND METHODS

Prolactin levels were measured daily for 4 days in 101 patients with sepsis. Delirium was assessed using the Richmond Agitation Sedation Scale and the Confusion Assessment Method in the ICU.

RESULTS

Delirium developed in 79 patients (78%) and was more common in patients older than 65 years. Prolactin levels were higher in patients with delirium than in those without over the 4 days of observation (P = .032). In patients with delirium, higher prolactin levels were associated with a lower incidence of nosocomial infection (P = .006). Multivariable logistic regression showed that the Sequential Organ Failure Assessment score at intensive care unit admission (odds ratio, 1.24; 95% confidence interval, 1.04-1.48; P = .002) and the combined effect of prolactin levels with age (odds ratio, 1.018; 95% confidence interval, 1.01-1.031; P = .006) were associated with the development of delirium.

CONCLUSIONS

High prolactin levels may be a risk factor for delirium in septic patients.

Delirium tremens, psychose parkinsonienne ou iatragénie ? Cas clinique de Mr T

Nous présentons le cas de Monsieur T., 58 ans, hospitalisé en soins psychiatriques à la demande d’un tiers, pour des troubles du comportement (agitation) et un vécu persécutif dans un contexte d’alcoolodépendance ancienne. Monsieur T. a pour principal antécédent une maladie de Parkinson diagnostiquée en avril 2014, traitée par ropinorole LP 8 mg/jour, trihexyphénidyl chlorydrate LP 10 mg/jour, et lévodopa/benzérazide chlorydrate aux doses de 125 mg trois fois/jour et 62,5 mg trois fois/jour. À l’arrivée, le patient rapporte des éléments délirants avec hallucinations visuelles hypnagogiques apparues cinq jours auparavant, après avoir arrêté toute consommation d’alcool. Nous observons une amélioration clinique après l’introduction de diazépam 40 mg/jour, vitaminothérapie et hydratation. Sept jours après l’admission, le patient présente un tableau confusionnel. Nous évoquons un délirium tremens et une iatrogénie des traitements parkinsoniens que nous arrêtons, nous doutons effectivement de l’observance du patient. La gravité des symptômes nécessite un transfert aux urgences. Sont décrits un délire de persécution, une fluctuation du contact et des confabulations malgré 60 mg/j de diazépam et une réhydratation. Un traitement par olanzapine 5 mg/j est initié. Il nous est ensuite réadressé. Nous notons des idées délirantes de persécution, des hallucinations acoustico-verbales vespérales, des comportements hétéro-agressifs, et une fluctuation du contact avec des périodes de confusion mêlant confabulations et faux souvenirs. Nous arrêtons l’olanzapine et instaurons très progressivement la quétiapine jusqu’à 600 mg/j, tout en réintroduisant le lévodopa/benzérazide chlorydrate. Chaque augmentation d’antiparkinsonien est marquée par une exacerbation temporaire des symptômes délirants. Le diazépam est arrêté. L’amélioration sera lente : disparition des troubles du comportement, éléments délirants critiqués, amélioration nette du contact. Le cas de Monsieur T. montre l’impact des traitements antiparkinsoniens sur la symptomatologie délirante. Si la clozapine est le traitement de première intention chez les patients parkinsoniens présentant une symptomatologie psychotique, nous avons préféré la quétiapine en raison de la comorbidité addictologique.

Minds on replay: musical hallucinations and their relationship to neurological disease

The phenomenon of musical hallucinations, in which individuals perceive music in the absence of an external auditory stimulus, has been described sparingly in the literature through small case reports and series. Musical hallucinations have been linked to multiple associated conditions, including psychiatric and neurologic disease, brain lesions, drug effect, and hearing impairment. This study aimed to review the demographics of subjects with musical hallucinations and to determine the prevalence of neurological disorders, particularly neurodegenerative disease. Through the Mayo medical record, 393 subjects with musical hallucinations were identified and divided into five categories based on comorbid conditions that have been associated with musical hallucinations: neurological, psychiatric, structural, drug effect and not otherwise classifiable. Variables, including hearing impairment and the presence of visual and other auditory hallucinations, were evaluated independently in all five groups. The mean age at onset of the hallucinations was 56 years, ranging from 18 to 98 years, and 65.4% of the subjects were female. Neurological disease and focal brain lesions were found in 25% and 9% of the total subjects, respectively. Sixty-five subjects were identified with a neurodegenerative disorder, with the Lewy body disorders being the most common. Visual hallucinations were more common in the group with neurological disease compared to the psychiatric, structural, and not otherwise classifiable groups (P < 0.001), whereas auditory hallucinations were more common in the psychiatric group compared to all other groups (P < 0.001). Structural lesions associated with musical hallucinations involved both hemispheres with a preference towards the left, and all but two included the temporal lobe. Hearing impairment was common, particularly in the not otherwise classifiable category where 67.2% had documented hearing impairment, more than in any other group (P < 0.001). Those with an underlying neurodegenerative disorder or isolated hearing impairment tended to hear more persistent music, which was often religious and patriotic compared to those with a structural lesion, where more modern music was heard, and those with psychiatric disorders where music was mood-congruent. This case series shows that musical hallucinations can occur in association with a wide variety of conditions, of which neurological disease and brain lesions represent a substantial proportion, and that Lewy body disorders are the most commonly associated neurodegenerative diseases. A future prospective study would be helpful to further delineate an association between musical hallucinations and neurodegenerative disease.

Anticholinergic burden in Parkinson's disease inpatients

PURPOSE

Anticholinergic toxicity can arise as a result of the cumulative burden of multiple medications and metabolites rather than be caused by a single compound. In this sense, prescribing drugs with anticholinergic properties to Parkinson's disease (PD) patients could contribute to aggravate some frequent problems of the disease, like dementia, urinary retention, falls, or constipation, among others. The main purpose of this article is to measure the total anticholinergic burden in a group of PD inpatients.

METHOD

We analyzed information from different administrative Basque Country's healthcare databases using encrypted unique identifiers in order to detect PD patients admitted to public acute care hospital during 2011-2012. Subsequently, anticholinergic burden was measured using Duran et al.'s list. Secondarily, total anticholinergic load was assessed with the Anticholinergic Drug Scale, the Anticholinergic Risk Score, and the Anticholinergic Burden Scale. A logistic regression model was performed to study association of predictive variables with anticholinergic use.

RESULTS

A high proportion of PD patients were prescribed anticholinergic drugs, with 53.6% of admissions receiving at least one drug from Duran et al.'s "low-risk" and 10% at least "high-risk" drug. Drugs used for non-motor symptoms and other comorbidities other than PD itself contributed significantly to anticholinergic burden, namely antidepressants, antipsychotics, urological drugs, analgesics, and antihistamines, among others. The total number of drugs and cholinesterase inhibitors were independently associated with anticholinergic drug use.

CONCLUSIONS

Anticholinergic burden in PD patients is significant, and is caused mostly by drugs not used for PD motor symptoms. Polypharmacy and cholinesterase inhibitors were independently associated with anticholinergic drug prescriptions.